Recently, there has been interest in the rapid sintering of nanoparticles using intense pulsed light (IPL) of non-coherent white light. This process, also known as photonic sintering and flash sintering, delivers rapid and high energy pulses of light to nanocomposite thin films. The absorbed light is transferred almost immediately to heat, sintering neighboring nanoparticles and resulting in a conductive film. The process differs significantly from laser sintering techniques in two distinct details: (1) a much larger spectrum of light spanning from the ultraviolet (UV) to the near infrared (NIR) is used; and (2) the processing area is significantly larger. Additionally, the nanoparticles can be deposited using known traditional solution-phase printing techniques over large areas. These considerations make the IPL process interesting for scalable manufacturing, especially roll-to-roll production.
Along these lines, conductive patterns printed using such solution-based processes also have the capability to drastically reduce production costs. This is especially relevant for large scale applications such as photovoltaics (PV) in which high throughput, efficient materials usage, and low energy techniques are needed to reduce the overall costs. In this regard, silver (Ag) is traditionally used in PV manufacturing due to its inherent stability in such a demanding application. The deposition of silver is typically accomplished using pastes followed by thermal treatment to produce conductive lines in a high-throughput process. Efforts to drive down the cost of the silver include reducing silver usage through optimizing the screen printing process and utilizing other schemes employed in the microelectronics industry. However, the photovoltaics industry still utilizes approximately 10 percent of the annual worldwide silver production with double digit compound annual growth rate expected to continue for the foreseeable future. Therefore, searches for lower cost earth abundant materials, such as copper or nickel, to replace silver are necessary to achieve and maintain positive profit margins. Nevertheless, a significant disadvantage to using copper as a direct replacement to silver in PV is copper's fast diffusion into silicon (Si), which results in a lower performance of the PC due to increased recombination of the minority carriers. To date, methods to overcome such diffusion of copper have included low temperature deposition techniques and incorporation of diffusion barrier layers, but have only yielded marginal successes.